Last month the city committed to shun investments in fossil fuels and shift to greener energies, alongside an international coalition of 40 Catholic organisations.

"The most important thing is (encouraging) people's belief that adopting a new lifestyle is important. One person's action will not have much impact (on climate change), but 7 billion actions can change the world," Proietti said.

Hanging on her office wall is former Pope John Paul II's proclamation making Francis, a 13th century monk, the patron saint of ecologists, and nearby sits a panda statue - a gift from the World Wildlife Fund.

Taking care of nature "is the Assisi responsibility" she said. "If we have a different message, then we are not (being true) to our history."

Proietti, who is a professor of energy systems at Rome's Guglielmo Marconi University, said she faces major challenges bringing about change in the city.

Its architectural heritage is one: houses cannot put solar panels on their roofs in this UNESCO world heritage site. The biggest challenge, though, is changing people's attitudes, she said.

"Assisi's people and administration never thought about this in the past," said Proietti, who was elected last year.

She plans to expand the city's heating grid that runs off a combined natural gas-fed heat and power plant in the valley below. The energy-efficient plant produces electricity and the resulting heat is piped to people's homes and city buildings.

She also plans to plant 1,000 trees around the valley's industrial zone, encourage the town's inhabitants to grow more plants in their homes, and promote the use of electric cars.

"I would like an electric car, but I cannot afford one," said Alice Scaglia, a 50 year-old Assisi artist and mother of three.

She has switched to low-energy bulbs, eats locally grown organic food and has cut back on meat. She said she wishes she could do more.

"It is a necessary revolution not only in Assisi but in the world," she said.

The saint's environmental bent inspired the current Pope Francis' choice of a name, and the Pope - who has been outspoken on the need to address climate change - has said he wants to continue Saint Francis' legacy.

"Assisi is a small town that starts to think about these problems," said Adriano Cioci, manager of Assisi's UNESCO office.

"But if the large entities in the world - including the United Nations, China, the United States, India - don't enter into this, the work of Assisi and other communes will be in vain," he said.

Saint Francis is buried in the city's basilica, the focus of pilgrims to the city and about 120 million people who join its services via a webcast each year.

Its custodians - monks from the Franciscan order - are converting the basilica, the seminary, and their home, to low energy lighting. Its famous frescoes painted by Giotto, and the saint's tomb are now lit with LED lighting.

They say their emissions have fallen 75 percent since work began in 2015.

"We want the Sacro Convento and the whole complex here to be an example to the city, the country, the world," said Father Enzo Fortunato, head of the Sacro Convento's press office.

They also hope to install solar panels to generate electricity, if they can get approval from the Ministry of Culture.

"It's important for us to respect the environment, because ultimately this is to respect man," said Fortunato.

"When you're saving the environment, you're creating an environment for people (to live and work in)."

"As the saint of ecology and the environment, St Francis transcends all religions," said Enzo.

On the main thoroughfare leading from the basilica to the mayor's office is a family restaurant serving local specialities such as risotto with mushrooms and truffles.

Cristiana Costantini, a journalist who was born and grew up in Assisi and helps out in the restaurant, says that the city must do its part to curb emissions and the already evident changes in the climate.

"The seasons no longer exist," she said.

On this autumn day she is working in a short-sleeved shirt, but remembers as a girl always having to wear a warm jacket outdoors at this time of year.

"Without St Francis, Assisi would be nothing but a beautiful ancient village, like so many others," she said.

"It is an international showcase of spirituality based on ... respect of other human beings and the surrounding environment in which they live," she said.

Costantini believes things are beginning to change, slowly. Low energy household appliances and light bulbs are popular in local shops and Assisi, along with neighbouring municipalities, is introducing electric car charging points.

This year, Italy, along with much of southern Europe, experienced severe drought, wildfires, and crop losses.

"The environment is going crazy" and it is the poor and homeless "who are the first to suffer the disastrous consequences of these climatic changes", she said.

Proietti will be presenting Assisi's plans at the international climate talks taking place in Bonn later this month.

"Assisi is a symbol for sustainability, mitigation of climate change, and it's the city of peace," she told the Thomson Reuters Foundation.